Quantum cascade laser system with power scaling and related methods and devices

Abstract

A quantum cascade laser may include a substrate, and a semiconductor layer adjacent the substrate and defining an active region. The active region may have an elongate shape extending laterally across the substrate and having first and second lowest injector states with an energy spacing greater than 20 meV. In some embodiments, the active region may have a thickness less than or equal to 1.3 μm and a length greater than or equal to 20 μm. The quantum cascade laser may also include an optical grating adjacent the active region and configured to emit a continuous wave laser output through the substrate. The optical grating may include a curved grating pattern.

That which is claimed is: 
     
       1. A quantum cascade laser (QCL) comprising:
 a substrate; 
 a semiconductor layer adjacent said substrate and defining an active region; and 
 said active region having an elongate shape extending laterally across said substrate and having first and second lowest injector states with an energy spacing being greater than 20 meV. 
 
     
     
       2. The QCL of  claim 1  wherein a thickness of said active region is less than or equal to 1.3 μm; and wherein a width of said active region is greater than or equal to 20 μm. 
     
     
       3. The QCL of  claim 1  wherein a low voltage, short injector design is used with stage thickness less than 40 nm. 
     
     
       4. The QCL of  claim 1  wherein an active region/injector coupling value exceeds 7 meV to increase dynamic range of the QCL. 
     
     
       5. The QCL of  claim 1  further comprising an optical grating adjacent said active region and configured to emit a continuous wave (CW) laser output through said substrate; and wherein said optical grating comprises a second order optical grating pattern. 
     
     
       6. The QCL of  claim 5  wherein said optical grating comprises a curved grating pattern based upon a phase function. 
     
     
       7. The QCL of  claim 5  wherein said optical grating is configured to emit the CW laser output at a power greater than or equal to 20 watts. 
     
     
       8. The QCL of  claim 1  wherein said active region has a tapered shape. 
     
     
       9. The QCL of  claim 1  wherein said active region has an angled shape. 
     
     
       10. The QCL of  claim 1  wherein said active region has a thickness of less than or equal to 1.2 μm. 
     
     
       11. The QCL of  claim 1  wherein said semiconductor layer comprises a plurality of layers defining a superlattice structure. 
     
     
       12. A quantum cascade laser (QCL) system comprising:
 a QCL comprising
 a substrate, 
 a semiconductor layer adjacent said substrate and defining an active region, and 
 said active region having an elongate shape extending laterally across said substrate and having first and second lowest injector states with an energy spacing being greater than 20 meV; and 
 
 a driver circuit coupled to said QCL. 
 
     
     
       13. The QCL system of  claim 12  wherein a thickness of said active region is less than or equal to 1.3 μm; and wherein a width of said active region is greater than or equal to 20 μm. 
     
     
       14. The QCL system of  claim 12  wherein a low voltage, short injector design is used with stage thickness less than 40 nm. 
     
     
       15. The QCL system of  claim 12  wherein an active region/injector coupling value exceeds 7 meV to increase dynamic range of the QCL. 
     
     
       16. The QCL system of  claim 12  wherein said QCL comprises an optical grating adjacent said active region and configured to emit a continuous wave (CW) laser output through said substrate; and wherein said optical grating comprises a second order optical grating pattern. 
     
     
       17. The QCL system of  claim 16  wherein said optical grating comprises a curved grating pattern based upon a phase function. 
     
     
       18. A method for making a quantum cascade laser (QCL) comprising:
 forming a semiconductor layer adjacent a substrate and defining an active region; and 
 the active region having an elongate shape extending laterally across the substrate and having first and second lowest injector states with an energy spacing being greater than 20 meV. 
 
     
     
       19. The method of  claim 18  wherein a thickness of said active region is less than or equal to 1.3 μm; and wherein a width of said active region is greater than or equal to 20 μm. 
     
     
       20. The method of  claim 18  wherein a low voltage, short injector design is used with stage thickness less than 40 nm. 
     
     
       21. A quantum cascade laser (QCL) comprising:
 a substrate; 
 a semiconductor layer adjacent said substrate and defining an active region; and 
 an optical grating adjacent said active region and configured to emit a laser output through said substrate, said optical grating comprising an optical grating pattern; 
 said active region having an elongate shape extending laterally across said substrate and having first and second lowest injector states with an energy spacing being greater than 20 meV. 
 
     
     
       22. A method for making a quantum cascade laser (QCL) comprising:
 forming a semiconductor layer adjacent a substrate and defining an active region; 
 
       the active region having an elongate shape extending laterally across the substrate and having first and second lowest injector states with an energy spacing being greater than 20 meV; and
 forming an optical grating adjacent the active region and configured to emit a laser output through the substrate, the optical grating comprising an optical grating pattern.